摘要
Sr、Nd、U等同位素体系被广泛应用于地球表生过程中年代测定及物源示踪等研究,高效地分离这些同位素体系,对于推广这些同位素方法的应用具有重要现实意义。若要同时分析地质样品中Sr、Nd、U三种元素的同位素,现有方法往往需要消解两份样品,一份用于Sr-Nd而另一份用于U的分离提纯。这种方法不但增加了样品用量,而且需要多次蒸干溶液转换介质,既延长了分离流程也增加了样品被污染的风险。为了提高样品利用率和分析效率,本文通过将树脂柱串联改进了分离流程,提出一种仅需消解一份样品,便可同时提取Sr、Nd、U三种元素的新方法。本方法中Sr的分离采用Sr特效树脂,包含Nd在内的稀土元素(REE)的分离采用AG50W-X8树脂,U的分离采用UTEVA特效树脂。实验中将三种树脂柱串联,采用3mol/L硝酸淋洗液淋洗,同步进行平衡树脂、上样、洗杂志,避免了蒸干操作。分离后的淋出液使用电感耦合等离子体质谱仪(ICP-MS)测试元素含量。结果表明:U的回收率接近99.9%,Sr的回收率超过90%,Nd的回收率超过80%;同时三种树脂柱串联的分离流程,主要基体元素(K、Ca、Na、Ba、Fe、Rb等)的去除率均超过99%,降低了对Sr、Nd、U高精度同位素分析的干扰;REE中的Sm则可以通过后续使用Ln树脂等进一步去除。此外,本文还交换了Sr特效树脂和UTEVA树脂的位置,比对两种不同串联顺序对分离结果的影响,结果表明两种树脂柱串联顺序对目标元素的分离并无显著影响。使用该方法可以有效地实现Sr、Nd、U的分离,在减少操作步骤的同时节省约一半的样品用量,提高了同位素分析效率。
BACKGROUND:Uranium-series nuclides are one of the three major radioactive decay systems,which are suitable for studying various geological processes at different time scales.In addition,87Sr/86Sr and143Nd/144Nd isotopes(Sr-Nd isotopes for short)are two commonly used isotopes,for rock dating,chemical weathering assessment and tracing sediment sources.In this case,the combination of Sr-Nd-U isotopes can provide more comprehensively knowledge of the element cycle on the earth’s surface and deepen our understanding of the sediment“Source to Sink”processes.Most previous studies involving the Sr-Nd-U isotopes have been established by separating Sr-Nd and U isotopes respectively.In this way,the digestion operation must be performed twice,one for separating Sr-Nd and the other for separating U.Alternatively,if only one sample is digested for measuring all three isotopes,between each element separation,the residue must be dried and dissolved in another solution so as to start a new column work.The former increases the amount of samples,which is not conducive to analysis of precious and trace samples;the latter adds additional drying operation,which is time consuming and increases the risk of sample loss and contamination.OBJECTIVES:To establish a new Sr-Nd-U combined separation scheme.In this method,only one sample is dissolved,avoiding solution transfer between each separation,so as to reduce sample amount and improve the efficiency of separation and purification of Sr-Nd-U isotopes.METHODS:A new chromatographic scheme of separating Sr-Nd-U with one sample digestion using a tandem column scheme is presented.Three columns were overlain sequentially to separate Sr in Sr Spec column,Nd in AG50W-X8 column and U in UTEVA column.3mol/L HNO3was used to pre-condition,load the sample,and rinse the matrix.After rinsing the matrix,the tandem column was separated to 3 independent columns to elute the target elements(Sr,Nd,U)respectively.As the connection sequence of different resin columns may interfere with the recovery of ta
作者
骆正骅
李超
赖正
王晨羽
郭玉龙
段知非
徐娟
杨守业
LUO Zhenghua;LI Chao;LAI Zheng;WANG Chenyu;GUO Yulong;DUAN Zhifei;XU Juan;YANG Shouye(State Key Laboratory of Marine Geology(Tongji University),Shanghai 200092,China;School of Ocean and Earth Sciences,Tongji University,Shanghai 200092,China;GFZ German Research Centre for Geosciences,Earth Surface Geochemistry,Telegrafenberg,Potsdam 14473,Germany)
出处
《岩矿测试》
CAS
CSCD
北大核心
2023年第1期102-113,共12页
Rock and Mineral Analysis
基金
国家自然科学基金项目(42076063,41991324)
上海市自然科学基金项目(20ZR1460400,21590712700)。
关键词
Sr
Nd
U
串联树脂
柱回收率
同位素分离
电感耦合等离子体质谱法
Sr
Nd
U
tandem resin column
column recovery
isotopic separation
inductively coupled plasma-mass spectrometry
